Zero-profile expandable intervertebral spacer devices for distraction and spinal fusion and a universal tool for their placement and expansion

ABSTRACT

A unique, universal Zero-Profile Expandable Intervertebral Spacer (ZP-EIS) device for fusion and distraction throughout the entire spine is provided which can be inserted via anterior, anterolateral, lateral, far lateral or posterior surgical approaches dependent on the need and preference. Multiple ZP-EIS embodiments each with unique mechanisms of calibrated expansion are provided. Two of these embodiments incorporate bi-directional fixating transvertebral (BDFT) screws and five other embodiments do not incorporate BDFT screws. A tool for implantation into the intervertebral device and calibrated device expansion is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-part Application of each ofco-pending application Ser. No. 13/210,150, filed on Aug. 15, 2011,co-pending application Ser. No. 13/210,157, filed on Aug. 15, 2011,co-pending application Ser. No. 13/210,162, filed on Aug. 15, 2011,co-pending application Ser. No. 13/210,168, filed on Aug. 15, 2011,co-pending application Ser. No. 13/741,361, filed on Jan. 14, 2013, eachof which is a Continuation Application of application Ser. No.13,084,543, filed on Apr. 11, 2011, now U.S. Pat. No. 8,353,913 issuedon Jan. 15, 2013, which is a Divisional Application of application Ser.No. 11/842,855, filed on Aug. 21, 2007, now U.S. Pat. No. 7,942,903issued on May 17, 2011, and a Continuation Application of applicationSer. No. 13,108,982, filed on May 16, 2011, which also is a ContinuationApplication of application Ser. No. 11/842,855, filed on Aug. 21, 2007,now U.S. Pat. No. 7,942,903 issued on May 17, 2011, which is aContinuation-In-Part Application of application Ser. No. 11/536,815,filed on Sep. 29, 2006, now U.S. Pat. No. 7,846,188 issued on Dec. 7,2010, which is a Continuation-In-Part Application of application Ser.No. 11/208,644, filed on Aug. 23, 2005, now U.S. Pat. No. 7,704,279issued on Apr. 27, 2010, for which priority is claimed under 35 U.S.C.§120; and this application also claims priority under 35 U.S.C. §119(e)of U.S. provisional application No. 61/801,783, filed on Mar. 15, 2013,U.S. provisional application No. 61/718,707, filed on Oct. 25, 2012, andU.S. provisional application No. 60/670,231, filed on Apr. 12, 2005; theentire contents of all the above identified patent applications arehereby incorporated by reference.

U.S. patent application Ser. No. 13/084,543, filed on Apr. 11, 2011,Ser. No. 11/842,855, filed on Aug. 21, 2007, Ser. No. 11/536,815, filedon Sep. 29, 2006, and Ser. No. 11/208,644, filed on Aug. 23, 2005, eachclaim the benefit of priority under 35 U.S.C. §119(e) of U.S.Provisional Application No. 60/670,231, filed on Apr. 12, 2005, and thisapplication hereby incorporates the claim of priority to thisprovisional application under 35 U.S.C. §119(e) from the aforementionedintermediate applications (for which priority of each intermediateapplication is claimed under 35 U.S.C. §120); and the entire contents ofall of the above identified patent applications are hereby incorporatedby reference in their entirety.

FIELD OF DISCLOSURE

The present invention relates to unique, universal Zero-ProfileExpandable Intervertebral Spacer (ZP-EIS) devices for fusion anddistraction throughout the entire spine which can be inserted viaanterior, anterolateral, lateral, far lateral or posterior surgicalapproaches dependent on the need and preference. Multiple ZP-EISembodiments each with unique mechanisms of calibrated expansion arepresented. Two of these embodiments incorporate bi-directional fixatingtransvertebral (BDFT) screws and five other embodiments do notincorporate BDFT screws. A universal tool for their intervertebralplacement and device expansion is also described.

The ZP-EIS embodiments with incorporated BDFT screws can be used asstand-alone intervertebral devices. These exemplary embodiments combinethe dual functions of intervertebral calibrated expandable distraction,and segmental vertebral body spinal fusion. These embodiments caninclude bone cavities which can be filled with bone fusion material(s)to promote segmental spinal fusion.

The calibrated ZP-EIS embodiments without incorporated BDFT screws canalso be used as stand-alone devices for calibrated intervertebralexpansion and segmental vertebral body fusion. The exemplary devices caninclude bone cavities which can be filled with bone fusion material. Ifdesirable, the exemplary devices can be supplemented with other forms ofscrew stabilization.

The exemplary ZP-EIS embodiments, especially those with incorporatedBDFT screws, may obviate the need for supplemental pedicle screwfixation in many situations. The exemplary embodiments allow nuanced,fine-tuned incremental and calibrated distraction of the disc space toallow nerve root decompression in a minimally invasive and safe manner,as well as promoting segmental spinal fusion.

In the related applications in the Cross-Reference to RelatedApplications, Applicants first introduced the terminology “zero-profile”relating to spinal fusion devices. Applicants also have describedzero-profile non-expandable and expandable stand-alone intervertebralspinal fusion device embodiments with incorporated BDFT screws. Asdescribed in greater detail below, exemplary embodiments of advancedZP-EIS devices with BDFT screws are provided which have an improvedcontoured body with tapered edges to more precisely insert into andconform to the biconcave disc space. The present application alsoprovides exemplary embodiments of more advanced ZP-EIS devices withoutaccompanying BDFT screws each with very unique calibrated expandablemechanisms allowing minimally invasive intervertebral expansion,vertebral body distraction and segmental spinal fusion. An exemplaryembodiment of a universal tool also is described that can be adapted toimplant one or more (e.g., all) of the intervertebral device embodimentsherein described into the intervertebral space, and mechanically expandthem.

BACKGROUND

The history and evolution of instrumented spinal fusion in the entirehuman spine has been reviewed in Applicants' copending applications setforth in the Cross-Reference to Related Applications (for example inU.S. Ser. No. 11/536,815, filed on Sep. 29, 2006, and Ser. No.11/208,644, filed on Aug. 23, 2005). Currently, the majority of spinalfusion techniques are typically supplemented with posterior pediclescrew placement and/or anterior (or lateral) plating. Complications ofpedicle screw placement in the spine may include duration of procedure,significant tissue dissection and muscle retraction, misplaced screwswith neural and/or vascular injury, excessive blood loss, need fortransfusions, prolonged recovery, incomplete return to work, and excessrigidity leading to adjacent segmental disease requiring further fusionsand re-operations. Recent advances in pedicle screw fixation includingminimally invasive and image-guided technology, and the development offlexible rods, imperfectly may address some but not all of these issues.

Anterior/and or lateral plating because of the plates' elevated profilescan be complicated by esophageal, or major vascular injury. Thezero-profile devices described herein with reference to the exemplaryembodiments avoid these complications.

Current non-expandable intervertebral spacers must be manufactured withdifferent heights, and the most appropriate sized spacer is selected forinsertion. In these situations, the vertebral bodies are forcefullydistracted to allow placement of an imperfectly fitting spacer. Theseare most often supplemented with pedicle screw and/or or plate fixation.

SUMMARY

The exemplary embodiments described herein can allow a more preciselytailored complimentary fit between spacer and disc space, allowing thespacer to expand gradually in a calibrated manner, and to incrementallyachieve the precise fit and degree of distraction desirable. Thus, theprocess according to the present invention can be more individualizedfor every patient and apply less forceful disruption to theintervertebral space thereby improving safety and enhancingeffectiveness of the placement of intervertebral spacers. The exemplaryembodiments are zero-profile, and thus, do not damage or indentoverlying soft tissue or vascular structures further decreasingmorbidity.

Herein described are exemplary embodiments of multiple ZP-EIS deviceswhich combine in a single construct the dual functions of calibratedexpandable intervertebral spacer distraction maintaining disc spaceheight, and simultaneous segmental vertebral body spinal fusion.

To achieve safe, effective zero-profile and minimally invasive segmentalspinal fusion, the exemplary embodiments of the present invention use ofnovel zero-profile calibrated expandable spacer (ZP-EIS) devices with orwithout BDFT screws which can be strategically inserted into theintervertebral disc space via anterior, anterio-lateral, lateral, farlateral or posterior surgical approaches.

In Applicants' applications set forth in the Cross-Reference to RelatedApplications, exemplary embodiments are directed to expandingintervertebral spacers which incorporated BDFT screws. One of theseembodiments includes two sliding triangular bases to house two screwsdriven in two opposing directions which can be expanded in twosimultaneous directions, height and depth, by turning a built-in screwadjuster. This was facilitated by a combined external drill/screwguide/cage expander to further enhance trajectory precision and tosimultaneously expand the screw box in height and depth to custom-fitthe individual disc space height. Applicants' copending applications setforth in the Cross-Reference to Related Applications further describe anexemplary embodiment of a universal tool and the adaptability of thetool, for example, to exemplary embodiments of sliding boxes, as well asto the exemplary embodiments described herein, including those with andwithout BDFT screws.

The evolved zero-profile expandable intervertebral spacer (ZP-EIS)embodiments with incorporated BDFT screws presented herein are morefinely tapered and contoured to more easily allow insertion andconformation to the biconcave disc space.

The exemplary embodiments of ZP-EIS devices without incorporated BDFTscrews described herein have the ability to incrementally and uniformlyseparate and distract the vertebral bodies. Each embodiment has a veryunique mechanically designed mechanism of incremental expansion. Thedevices are all designed with cavities for bone fusion giving thesurgeon the option to use these as stand-alone fusion/spacer devices oras supplemental devices if other screw fixation is deemed necessary.These innovations represent a continued evolution of our concept ofzero-profile calibrated expandable intervertebral distraction/fusionspacers described in Applicants' applications, for example, as set forthin the Cross-Reference to Related Applications.

In the exemplary ZP-EIS embodiments with incorporated BDFT screws, arostral-directed screw is passed through one built-in screw guide of thedevice which then is inserted and screwed into the superior vertebralbody. Next, a caudally directed screw is passed through an adjacentbuilt-in screw guide, which then is inserted and screwed into theinferior vertebral body. One of many novels features of this design isthe built-in prescribed angles of the integral screw guides which allowthe transvertebral penetration into the vertebral bodies. This is atruly amazing feat accomplished particularly in the posterior orlateral/far lateral lumbar spine considering the small anatomicallyrestricted work zone within which to work, which is very narrowlyprescribed by obtuse angulations between screw and intervertebral bonesurfaces, and by nerve root, facet joint and pedicle. Applicants'applications set forth in the Cross-Reference to Related Applicationsincluded an angled screw driver specifically designed to fit thesedevices if a straight screw driver impedes screw placement. Hence, theseexternal tools can provide the means in any circumstance to accomplishprecision screw trajectory.

The exemplary zero-profile embodiments of the present invention canprovide enhanced individualized intervertebral conformation, andmultiple methods of finely calibrating intervertebral expansion, andvertebral body distraction further reducing morbidity and enabling moreminimally invasive surgical methods of vertebral body distraction andsegmental fusion compared to Applicants' applications set forth in theCross-Reference to Related Applications.

The exemplary embodiments of box casings can include perforations toallow bone packing for fusion. These exemplary devices can preventsubsidence. In an exemplary embodiment, both the inside of the denudedintervertebral space, and the devices can be packed with autologous orallograft bone, BMP, DBX or similar osteoconductive material.

The zero-profile EIS embodiments, in particular those with incorporatedBDFT screws, can provide as strong or stronger segmental fusion aspedicle screws without the complications arising from pedicle screwplacement which include screw misplacement with potential nerve and/orvascular injury, violation of healthy facets, possible pedicledestruction, blood loss, and overly rigid fusions. In the case of theposterior Lumbar spine by placing screws across the intervertebral spacefrom vertebral body to vertebral body, engaging anterior and middlespinal columns, and not the vertebral bodies via the transpediclarroute, the healthy facet joints, if they exist, are preserved. Becausethe exemplary techniques accomplish both anterior and middle columnfusion, without rigidly fixating the posterior column, the exemplaryembodiments in essence create a flexible fusion. This exemplary devicestherefore can provide a flexible fusion device because the preservedposterior facet joints retain their function achieving at least amodicum of mobility and hence a less rigid (i.e. a flexible) fusion.

The very advantage of transpedicular screws which facilitate a strongsolid fusion by rigidly engaging all three spinal columns is the samemechanical mechanism whereby complete inflexibility of all columns isincurred thereby leading to increasing rostral and caudal segmentalstress which leads to an increased rate of re-operation.

Transvertebral fusion also leads to far less muscle retraction, bloodloss, and significant reduction in operating room (O.R.) time. Thus, thecomplication of pedicular screw pull-out and hence high re-operationrate associated with the conventional flexible fusion pediclescrews/rods is obviated.

Although the exemplary embodiments can be supplemented withtranspedicular screws, there would be no absolute need for supplementalpedicle screw fixation with these operative techniques. The expandablespacers without BDFT screws can be supplemented with other screwstabilization if desired.

Because the exemplary embodiments are zero-profile, these devices alsoobviate the morbidity involved with profiled anterior or lateralplating. Multi-level fusions can be performed with all of the exemplaryembodiments described herein.

Currently failed anterior lumbar arthroplasties are salvaged by combinedanterior and posterior fusions. The exemplary ZP-EIS embodiments withincorporated BDFT screws could be utilized as a one-step salvageoperation for failed/extruded anteriorly placed lumbar artificial discsobviating the above salvage procedure which has far greater morbidity.

BRIEF DESCRIPTION OF DRAWINGS

These and other aspects and features of embodiments of the presentinvention will be better understood after a reading of the followingdetailed description, together with the attached drawings, wherein:

FIGS. 1A-1B illustrate an exemplary embodiment (Embodiment I) of anon-tapered sliding base ZP-EIS device with incorporated BDFT screws insagittal-oblique (FIG. 1A), and exploded (FIG. 1B) views.

FIGS. 2A-2D illustrate an exemplary embodiment (Embodiment II) of atapered sliding base ZP-EIS device with incorporated BDFT screws inclosed (FIG. 2A), semi-expanded (FIG. 2B), and fully expanded (FIG. 2C)positions, and in an exploded view (FIG. 2D).

FIGS. 3A-3D illustrate an exemplary embodiment (Embodiment III) of ascissors jack driven ZP-EIS device without incorporated BDFT screws inclosed (FIG. 3A), semi-expanded (FIG. 3B), and fully expanded (FIG. 3C)positions, and in exploded view (FIG. 3D).

FIGS. 4A-4C illustrate an exemplary embodiment (Embodiment IV) of atapered thread driven ZP-EIS device without incorporated BDFT screws inclosed (FIG. 4A), semi-expanded/fully expanded positions (FIG. 4B), andin cross-sectional view (FIG. 4C).

FIGS. 5A-5D illustrate an exemplary embodiment (Embodiment V) of a dryanchor driven ZP-EIS device without incorporated BDFT screws in closed(FIG. 5A), semi-expanded (FIG. 5B), and fully expanded (FIG. 5C)positions, and in an exploded view (FIG. 5D).

FIGS. 6A-6D illustrate an exemplary embodiment (Embodiment VI) of amodified wedge driven ZP-EIS device without incorporated BDFT screws inclosed (FIG. 6A), semi-expanded (FIG. 6B), and fully expanded (FIG. 6C)positions, and in an exploded view (FIG. 6D).

FIGS. 7A-7D illustrate an exemplary embodiment (Embodiment VII) of aworm drive ZP-EIS device without incorporated BDFT screws in closed(FIG. 7A), semi-expanded (FIG. 7B), and fully expanded (FIG. 7C)positions, and in an exploded view (FIG. 7D).

FIGS. 7E(i) and 7E(ii) illustrate top, perspective views of anintervertebral cage construct according to an exemplary embodiment ofthe invention.

FIG. 8A-8C illustrate a positioning tool/screw guide/box expander inoblique perspective (FIG. 8A), lateral (FIG. 8B), and exploded (FIG. 8C)views according to an exemplary embodiment, which is shown coupled tothe exemplary non-tapered sliding base ZP-EIS device illustrated inFIGS. 1A-1B.

FIGS. 8D(i) and 8D(ii) illustrate superior oblique perspective views ofthe positioning tool/drill guide/box expander component, according to anexemplary embodiment, which may be optionally used for the exemplaryembodiments illustrated in FIGS. 1A-1B and 2A-2D.

FIGS. 8E-8G illustrate sequential steps (I-III: Step I (FIG. 8E), stepII (FIG. 8F), and step III (FIG. 8G)) of the positioning tool/screwguide/box expander assembly according to an exemplary embodiment.

FIGS. 8H-8I illustrate three-dimensional views of positioning tools,according to exemplary embodiments, for impaction and placement of twotransvertebral screws, for example, of the exemplary embodimentsillustrated in FIGS. 1A-1B and 2A-2D.

FIGS. 8J-8K illustrate the insertion of expandable Lumbar bi-directionalscrew box with two BDFT screws into the Lumbar spine in oblique (FIG.8J) and lateral (FIG. 8K) views.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now is described more fully hereinafter withreference to the accompanying drawings, in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

1. The Medical Device

Referring now to the drawings, FIGS. 1A-8K illustrate exemplaryembodiments of ZP-EIS devices that can solve the above describedproblems and others in the spine by insertion of the ZP-EIS devices intothe denuded intervertebral disc space according to the featuresillustrated in the exemplary embodiments (I-VII).

FIGS. 1A-1B illustrate three-dimensional views of a ZP-EIS device 100according to embodiment I, with two BDFT screws 101, 102.

The expandable ZP-EIS device 100 includes of top and bottom triangularsliding bases 103, 104 (FIGS. 1A-1B). The superior and inferior segmentsof the height/depth adjusting screw 105 are integrated and connected tothe two separate top and bottom triangular bases 103, 104, respectively.By turning this adjusting (rotation) screw 105 back and forth, i.e.clock-wise, and counter clockwise, the sliding rails 106 of the toptriangular base 103 (FIGS. 1A-1B) slide up and down the rail inserts 107on the bottom triangular base 104 (FIGS. 1A-1B). This action willsimultaneously alter the intervertebral height and depth of the device100 allowing individualized custom fitting of the ZPEIS device 100conforming to the dimensions of the disc space.

A transvertebral screw 101 penetrates the top base 103, and atransvertebral screw 102 traverses the bottom base 104 of the screw box(device 100). The two screws 101, 102 traverse the screw box 100 inopposing directions, bi-directionally. The external edges of thetriangular bases 103, 104 in contact with vertebral body surfaces caninclude ridges 107, which facilitates the ZP-EIS device 100incorporation into and fusion with the superior and inferior vertebralbodies (FIGS. 1A-1B). Both top and bottom ZP-EIS bases 103, 104 can beperforated with holes 108 to allow bone placement for fusion. In anexemplary embodiment, the entire construct, furthermore, can be hollowto allow filling with bone filling material. Hence, the exemplary devicefunctions as both an intervertebral bone fusion spacer andbi-directional transvertebral screw fusion device.

FIGS. 2A-2D illustrate a ZP-EIS device 200 according to exemplaryembodiment II. This exemplary device 200 incorporates BDFT screws andemploys a fusion wedge mechanism of expansion.

The device 200 includes a contoured top 208 and bottom 206 housing whichhave tapered edges and are coupled to each other by a diagonal dovetailinterface 204 which constrains the components 208, 206 to translatelinearly relative to each other. The linear translation causes avertical separation of the top 208 and bottom 206 housing surfaces whichare parallel to each other. The position is secured and adjusted by athreaded rotation screw 220 coupled to a nut 224 and a retaining ring222 and passed through the top 208 and bottom 206 housing pieces. As thethreaded rotation screw 220 is rotated further into the nut 224, thehousing pieces 208, 206 expand vertically.

By turning this adjusting (rotation) screw 220 back and forth i.e.clock-wise, and counter clockwise, the sliding rails 210 of the tophousing piece 208 slide up and down the rail inserts 212 on the bottomhousing piece 206. This action will simultaneously alter theintervertebral height and depth of the device 200 allowingindividualized custom fitting of the ZP-EIS conforming to the dimensionsof the disc space. A transvertebral screw 101 penetrates the top housingpiece 208, and a transvertebral screw 102 traverses the bottom housingpiece 206 of the device 200. The two screws 101, 102 traverse the device200 in opposing directions, bi-directionally. The external edges of thehousing pieces in contact with vertebral body surfaces include ridges216. This facilitates the ZP-EIS device 200 incorporation into andfusion with the superior and inferior vertebral bodies (FIGS. 2A-2D).Both top and bottom ZP-EIS housing bases 208, 206 are perforated withholes 214 to allow bone placement for fusion. The entire device 200,furthermore, can be hollow to allow bone filling. Hence, the exemplarydevice 200 functions as both an intervertebral bone fusion spacer andbi-directional transvertebral screw fusion device.

The device 200 can include a tapered edge 226 (shown for example inFIGS. 2A-2B), which allows easier introduction and insertion of thedevice 200 into the disc space.

FIGS. 3A-3D illustrate a ZP-EIS device 300 according to exemplaryembodiment III, which employs a scissor jack expansion mechanism.

In this embodiment the top 302 and bottom 304 housing are attached byone internal linkage arm 310, and two external linkage arms 308. Thedevice 300 can include indentations 306 on each lateral side close tothe top of the device 300 to mate with the prongs of the universal tool(for example, as described in FIGS. 8A-8I) to assist in grasping,inserting and impacting the device 300. A lead screw or rotation screw314 is mounted in the bottom housing 304 and secured in place with aretaining ring 316. When the lead (rotation) screw 314 is rotated by anexternal tool (for example, as described in FIGS. 8A-8I), the screw 314causes the linear displacement of the separation block 318 which ishinged to the internal linkage 310. The horizontal motion of theseparation block causes the top 302 and bottom 304 housing pieces toseparate vertically. The separation distance depends on the amount ofrotation of the lead (rotation) screw 314, and is limited by the freedomof the separation block 318 to move within the bottom housing 304. Theexemplary embodiment can include a plurality of pins, such as eight pins320, 322, 324, to secure the external linkage arms 308 to the top 302and bottom 304 housing units and to the separation block 318. The tophousing 302 and bottom housing 304 can include one or more cavities 312for bone incorporation/fusion.

FIGS. 4A-4C illustrate a ZP-EIS device 400 according to exemplaryembodiment IV, which employs a tapered thread mechanism of expansion.

The exemplary device 400 can include a top housing 402 and bottomhousing 404, which can be attached by one or more pins, such as two pins412, which allow rotation of the top housing 402 and bottom housing 404relative to each other about the axis of the pins 412. The top housing402 and/o bottom housing 404 can include indentations 406 on theirlateral sides close to the top of the device 400 to mate with the prongsof a tool or universal tool (e.g., prongs 806 in FIGS. 8A-8I) to assistin grasping, inserting and impacting the device 400. The bottom housing404 can include a mount for the rotation screw 410 (FIG. 4C), which cancontrol the relative angular orientation of the two housing pieces 402,404. When the screw 410 is rotated by an external tool (e.g. as shown inFIGS. 8A-8I), the screw 410 engages the internal teeth/ridges 414 of thetop housing 402 and acts as a wedge to rotate the top housing 402 awayfrom the bottom housing 404. More particularly, the device 400 caninclude a sloped ridge 414, as exemplary illustrated in FIG. 4C. Whenthe rotating screw 410 advances, the top housing 402 rotates further andfurther away from the bottom housing 404. The device 400 can include oneor more bone cavities in the top housing 402 and bottom housing 404 forbone fusion.

FIGS. 5A-5D illustrate exemplary embodiments of a ZP-EIS deviceaccording to embodiment V, which employs an anchor mechanism ofexpansion.

The top housing 502 and bottom housing 504 can be coupled or attached byone or more pins, such as two pins 512, which allow rotation of the tophousing 502 and bottom housing 504 relative to each other about the axisof the pins 512. The top housing 502 and/or the bottom housing 504 caninclude indentations 506 on their lateral sides close to the top of thedevice 500 to mate with the prongs of a tool or universal tool (e.g. seeFIGS. 8A-8I) to assist in grasping, inserting and impacting the device500. The bottom housing 504 can include, for example, a mount for thelead (rotation) screw 510, which can control the relative angularorientation of the two housing pieces 502, 504. The lead (rotation)screw 510 can be secured with one or more retaining rings, such as tworetaining rings 518. When the screw 510 is rotated by an external tool(not illustrated)(e.g., such as the tool shown in FIGS. 8A-8I), thescrew 510 causes lateral motion of a translation nut 516, which isattached to two linkage bars 514 to a second nut 516 fixed to the bottomhousing. A plurality of pins, such as six pins 512, can secure thelinkage bars or arms 514 to each other and to translation nuts 516. Whenthe translation nuts 516 move, the linkage bars or arms 514 extendoutside of the bottom housing 504, pushing against the top housing 502.Alternatively, in other embodiments, the linkage bars or arms 514 can bereplaced by a solid material such as spring steel which can bend toproduce the same effect. The device 500 can include one or more bonecavities that can be incorporated into the top housing 502 and thebottom housing 504 for bone fusion.

FIGS. 6A-6D illustrate exemplary embodiments of a ZP-EIS device 600according to embodiment VI which employs a modified wedge expansionmechanism.

The device 600 includes a top housing 602 and a bottom housing 604 thatcan be attached or coupled by one or more pins, such as two pins 612,which allow rotation of the top housing 602 and the bottom housing 604relative to each other about the axis of the pins 612. The top housing602 and/or the bottom housing 604 can include indentations 606 on theirlateral sides close to the top of the device 600 to mate with the prongsof a tool, such as prongs 806 of the universal tool shown in FIGS.8A-8I, to assist in grasping, inserting and impacting the device 600.The bottom housing 604 can include a mount for the lead (rotation) screw610, which can control the relative angular orientation of the twohousing pieces 602, 604. The lead (rotation) screw 610 can be securedwith one or more retaining rings, such as two retaining rings 618. Whenthe screw 610 is rotated by an external tool (e.g., the tool shown inFIGS. 8A-8I), the screw 610 causes lateral motion of a wedge-shapedtranslation nut 616. The nut 616 engages an inner tapered surface of thetop housing 602 and forces the top housing piece 602 to rotate away fromthe bottom housing 604. The device 600 can include one or more bonecavities 608 incorporated into the top housing 602 and/or bottom housing604 for bone fusion.

FIGS. 7A-7D illustrate exemplary embodiments of a ZP-EIS device 700according to embodiment VII, which employs a worm drive (gear)mechanism.

According to the invention, the device 700 includes a worm drive designthat allows a user to rotate a worm gear/drive 712 with an external tool(FIG. 8) to control the translation of the top housing 702 relative tothe bottom housing 704 a, 704 b. The worm gear drive 712 engages a spurgear mount 714 which has internal threading for engaging a correspondingpart, such as a threaded stud of bolt 720, to couple the spur gear mount714 to the top housing 702. The top housing 702 can include a pluralityof pins, such as four pins 712, which extend into the bottom housing 704a, 704 b. These pins 712 prevent the top housing 702 from rotating withthe spur gear 714, and constrain the spur gear 714 to translatelinearly. The bottom housing 704 can include two halves 704 a, 704 b tosecure the worm drive 710 and spur mount 714 in place. A worm retainingring and a spur retaining ring 716 also can be used to secure the wormgear drive 710 and the spur gear mount 714. The device 700 can includeone or more bone cavities 708 that are incorporated into the top housing702 and/or bottom housing 704 a, 704 b for bone fusion. The top housing702 and/or bottom housing 704 a, 704 b can include one or moreindentations 706 on its lateral sides close to the top of the device 700to mate with prongs of a tool, such as prongs 806 of the universal tool800 in FIGS. 8A-8I, to assist in grasping, inserting and impacting thedevice 700.

FIGS. 8A-8C illustrate three-dimensional views of exemplary embodimentsof the external drill/screw guide-box expander universal tool 800 whichcan be used to assist in both screw trajectory and box expansion of anexpandible device, such as the exemplary embodiments of devicesillustrated in embodiments I and II, and for device expansion of thedevices illustrated in embodiments III-VII. The same universal tool 800can be utilized for all the exemplary embodiments illustrated inembodiments I-VII. In some embodiments, the external drill/screw guide850 may not be needed or used for embodiments II-VII. The prongs 806 canbe inserted into the indentations (e.g., 202, 306, 406, 506, 606, 706)of the sides of the devices (e.g., 100, 200, 300, 400, 500, 600, 700)according to one or all of the exemplary embodiments illustrated inembodiments I-VII, and implant the device into the intervertebral space.Once implanted and impacted, an Allen key (e.g., as shown in FIG. 8) canbe used to expand the device (e.g., 100, 200, 300, 400, 500, 600, 700)by turning the adjustment (rotation) screw (e.g., 105, 220, 314, 410,510, 610, 710).

The exemplary tool can include, among other things, an Allen key 801, aspring 802, a handle 803, a griper 804 and a screw guide 805. The Allenkey 801, when inserted in the insertion 814 and turned, can turn therotation screws (e.g., 105, 220, 314, 410, 510, 610, 710) of one or allof the exemplary embodiments I-VII. The griper 804 includes griperprongs 806, which insert into grooves 509 of the screw guide 805 and thescrew box indentations (e.g., 202) in the exemplary embodimentillustrated in embodiment I (as shown in FIGS. 8A-8D), as well as insimilar indentations (e.g., 306, 406, 506, 606, 706) of devices (e.g.,100, 200, 300, 400, 500, 600, 700) illustrated in embodiments II-VII(not shown).

As shown in FIG. 8C, each longitudinal end of the screw box 100 caninclude a slot or indentation 108 formed adjacent to an edge of an uppersurface of the screw box 100 for engaging a protuberant extension of atool, such as the protuberant extension 807 of the tool 800.

FIG. 8D illustrates a superior oblique view of the screw guide 805demonstrating insertions 809 for griper prong 806, built-in trajectoryguides 811, 812 for insertion of screws 101 and 102, and the Allen key801. This exemplary embodiment can be limited, for example, to use withthe devices of embodiments I and II, which includes BDFT screws.

FIGS. 8E-8G illustrate three-dimensional views of the sequential stepsnecessary for the external guide assembly. FIG. 8E illustrates theinsertion of the Allen key 801 into the handle 803. FIG. 5F illustratesthe insertion of the handle 803 through the spring 802 and griper 804.FIG. 8G illustrates insertion of the griper 804 into the screw guide805. The griper prongs 806 can include medially oriented maleprotuberant extensions 807 that engage the slot or indentation of adevice, such as indentation 108 of device 100, thereby perfectlyaligning the prongs 805 of the tool 800 with the device (e.g., 100, 200,300, 400, 500, 600, 700). This exemplary embodiment can be limited, forexample, to use with the devices of embodiments I and II.

FIG. 8H illustrates a three-dimensional view of another exemplaryembodiment of a positioning tool 800 for impaction and placement of twotransvertebral screws 201, 202 for example, for use with the exemplaryembodiments I and II.

With reference again to FIGS. 8A-8K, the screw guide 805 can includeinsertions 809 for receiving the griper prong 806, built-in trajectoryguides 811, 812 for insertion of screws 101 and 102, and the Allen key801.

The driver assembly 850 can include a screw driver 851, a flexible shaft852 and a square recess bit 853. This exemplary device can facilitateturning the screws 101, 102 into the bone. The flexible shaft 852 canfacilitate the avoidance of spinous processes which might hinder thescrew driving if the shaft 852 were straight. The positioning tool 800can have a rectangular handle, as shown for example in Embodiment I, ora circular handle, as exemplary shown in Embodiment II. This exemplaryembodiment can serve to position a screw box within the intervertebralspace, and screws 101, 102 within the screw box or device. Oncepositioned, the screw box or device (e.g., 100, 200, 300, 400, 500, 600,700) can be impacted by tapping the handle 803 with a mallet (notshown). The griper handle 803 inserts into the screw guide and the screwbox or device (e.g., 100, 200, 300, 400, 500, 600, 700), which maintainsalignment.

2. The Surgical Method

Exemplary embodiments of a surgical method for utilizing the exemplarydevices described herein, will now be described. The procedures can beperformed open, microscopic, closed tubular or endoscopic. Fluoroscopicguidance can be used with any of these procedures.

An exemplary embodiment of a ZP-EIS device, as illustrated inembodiments (I-VII), can be inserted into the intervertebral space (forexample as shown in FIGS. 8J and 8K) after an adequate discectomy isperformed in any disc space throughout the entire spine upon theirexposure anteriorly, anterio-laterally, laterally, far laterally orposteriorly.

For exemplary embodiments I-II of the ZP-EIS devices can be insertedinto the disc space by a tool or universal tool, such as the universaltool 800 in FIGS. 8A-8I. In operation, the grab prongs of tool 800 canattach to the insets or indentations (e.g., 202, 306, 406, 506, 606,706) on the side of the devices. Once in the disc space, the rotationscrew (e.g., 105, 220, 314, 410, 510, 610, 710) of each embodiment isturned by rotating the Allen key 801 of the tool 800 to expand thedevice (e.g., 100, 200, 300, 400, 500, 600, 700) to the desirable discheight achieving the desirable intervertebral distraction deemednecessary for the individual patient and disc space. Once this isachieved, BDFT screws 101, 102 are inserted and screwed into thevertebral body above and below securing the device (e.g., 100, 200, 300,400, 500, 600, 700) to the vertebral bodies with screws 101, 102. Priorto implantation of the device (e.g., 100, 200, 300, 400, 500, 600, 700),the bone cavities of each device can be filled with any type of bonefusion material.

For the exemplary embodiments III-VII, the ZP-EIS device (e.g., 100,200, 300, 400, 500, 600, 700) can be inserted into the disc space by thesame universal tool, such as tool 800. The grabs prongs 806 of the tool800 attach to the insets or indentations (e.g., 202, 306, 406, 506, 606,706) on the side of the devices (e.g., 100, 200, 300, 400, 500, 600,700) on the side of the devices (e.g., 100, 200, 300, 400, 500, 600,700). Once in the disc space, the rotation screw (e.g., 105, 220, 314,410, 510, 610, 710) is turned by rotating the Allen key 801 of the tool800 expanding the device (e.g., 100, 200, 300, 400, 500, 600, 700) tothe desirable disc height achieving the desirable intervertebraldistraction deemed necessary for the individual patient and disc space.Prior to implantation of the device (e.g., 100, 200, 300, 400, 500, 600,700) the bone cavities of each device (e.g., 100, 200, 300, 400, 500,600, 700) can be filled with any type of bone fusion material.

The exemplary embodiments of the present invention may provide effectiveand safe techniques that overcome the problems associated with currenttranspedicular and/or plated fusion technology employed for manydegenerative stable and unstable spine diseases. These exemplaryembodiments may replace much pedicle screw-based and plated basedinstrumentation in many but not all degenerative spine conditions.

The speed and simplicity of the surgical implantation of the exemplaryembodiments of the ZP-EIS devices far exceeds that of conventionalpedicle screw technology. Furthermore, the exemplary embodiments ofzero-profile devices can provide markedly significantly decreased riskof misguided screw placement, and hence decreased risk of neural andvascular injury, and blood loss. The exemplary embodiments can providedecreased recovery and back to work time. The exemplary embodiments ofdevices may lead to similar if not equal fusion with significantly lessmorbidity, and hence overall make the exemplary devices a major advancein the evolution of spinal instrumented technology leading to advancesin the care of the spinal patient.

According to the exemplary embodiments, such as the embodiments inembodiments I and II, an intervertebral fusion device is provided thatuses a threaded rod mechanism located at the peripheral of the box tocontrol expansion of the device. The device can include a cavity withinthe walls for placement of bone material for fusion.

In another embodiment, an intervertebral fusion device can include athreaded rod which can obstruct (inhibit) expansion of the device whenit is not being turned. The threaded rod can be disposed at the frontanterior part of the box or device.

In yet another embodiment, an intervertebral fusion device can include athreaded rod, which exerts a clamping force to expand the device untilthe device properly accommodates the dimensions of the intervertebraldisc space and distracts the space based on individual anatomy andsurgical judgment. The device can include a cavity for bone in-betweenthe walls of the box.

In another embodiment, an expandable intervertebral fusion device canincludes indentations on its sides to accommodate a placement tool.

In another embodiment, an expandable intervertebral fusion device can beadjusted by using a threaded rod as a wedge to pivot components withinthe device. The threaded rod can be accessible from the front anteriorof the box or device.

In another embodiment, an expandable fusion device can include athreaded rod to expand a spacer. The threaded rod can be used as a wedgeto mechanically separate the pieces. The threaded rod can be accessiblefrom the front anterior of the box or device.

In another embodiment, an expandable fusion device can include wedgecomponents which translate relative to each other along a contact. Thedegree of expansion can be determined by an adjustment rod located atthe peripheral of the box or device.

In another embodiment, an expandable fusion device includes componentswhich are mechanically linked together. The expansion of the device iscontrolled by the user via an adjustment rod coupled to a mechanicaltransmission that causes mechanical components within the device toseparate. The threaded rod is accessible from the front anterior of thebox or device.

In another embodiment, an expandable fusion device can be providewherein the position of the device is secured and adjusted by a threadedrod that is mechanically linked to housing pieces. When the threaded rodis rotated, the threaded rod forces the pieces to separate.

In another embodiment, an intervertebral fusion device is providewherein the two internal screw guides are in the top housing unit.

In another embodiment, an intervertebral fusion expansile device isprovided wherein the center of the two internal screw guides could be inquadrants I and III or II and IV.

In another embodiment, an expandable fusion device can be provided thatuses a threaded rod (rotation screw) to expand the device using a metaldriver as the wedge to mechanically separate the pieces.

In another embodiment, an expandable fusion device can be adjusted byusing a threaded rod (rotation screw) as a wedge to offset the opposingcages.

In another embodiment, an expandable intervertebral fusion device can beprovided wherein its position is secured and adjusted by a threaded rod(rotation screw) coupled to a nut and passed through the top and bottomhousing pieces. As the threaded rod is rotated further into the nut, thepieces separate.

In another embodiment, an expandable intervertebral fusion device caninclude a tapered edge to allow contoured insertion into the disc space.

In another embodiment, an intervertebral fusion device can be providedwherein the internal screw guides for screw insertion within the deviceare diagonal to each other within the xyz plane.

In another embodiment, an intervertebral fusion device wherein theinternal screw guides can be adjacent and somewhat diagonal to eachother within the xyz plane.

In another embodiment, an intervertebral fusion device can be providedwherein the majority each of the 2 screw holes can be in quadrant I andIII or II and IV within the xyz plane.

In another embodiment, an intervertebral fusion device can be providedwherein the screw guides can have approximately the same xy coordinatesand have different z coordinates or vice versa.

In another embodiment, an intervertebral fusion device can be providedwherein the center of the two internal screw guides could be inquadrants I and III or II and IV within the xyz plane.

In another embodiment, an intervertebral fusion device can be providedwherein one screw guide is in the top housing unit, and another screwguide is in the bottom housing unit.

In another embodiment, an intervertebral fusion device can be providedthat uses a threaded rod (rotation screw) to engage a moveable componentwhich engages a linkage to expand the device.

In another embodiment, an intervertebral fusion device can be providedthat uses a threaded rod (rotation screw) to engage a wedge whichengages its attaching linkages to expand the device.

In another embodiment, an expandable fusion device can be provided thatcan be adjusted using a threaded rod (rotation screw) coupled to ascissor-jack linkage.

In another embodiment, an expandable fusion device can be held togetherwith fastener (s). These fasteners constrain the box to one degree offreedom. Part of the mechanism contains a mount for the rotation screw,which can control the movement of the pieces. As the screw is turned, itengages the teeth of the mechanism and acts as a wedge to rotate thepieces away from each other.

In another embodiment, an expandable fusion device adjusted by using athreaded rod (rotation screw) can be used as a wedge to offset theopposing cage surfaces.

In another embodiment, an expandable fusion device can be provided thatuses a threaded rod (rotation screw) to expand the device using a metaldriver as the wedge to mechanically separate the pieces.

In another embodiment, an expandable fusion device can be provided thatcan be adjusted by a threaded rod (rotation screw) coupled to a nutwhich translates to deform an elastomeric material used to force theexpansion of the device.

In another embodiment, an expandable fusion device can be provided thathas a threaded rod (rotation screw) that engages a wedge to control theexpansion of the device.

In another embodiment, an expandable fusion device can be provided thatcan be contained by fasteners and retaining rings.

In another embodiment, an expandable fusion device can be provided thatcan be adjusted by a threaded rod (rotation screw) coupled to a wedgethat can move the opposing cage surfaces.

In another embodiment, an expandable fusion device can be provided thatuses a worm drive to turn a gear that acts as a wedge to expand thedevice.

In another embodiment, an expandable fusion device can be provided thatincludes fasteners and retaining rings containing and constraining thedevice pieces.

In another embodiment, an expandable fusion device can be provided thatcan be adjusted by a worm gear coupled to an internally threaded spurgear which, upon rotation, linearly advances a threaded component.

In another embodiment, a tool includes a handle, a gripper cooperatingwith the handle and having a plurality of prongs, a screw guide held inplace the plurality of prongs, for controlling the direction ofself-drilling screws that are screwed into the vertebral bodies, and anAllen key which expands expandable intervertebral devices.

The present invention has been described herein in terms of severalpreferred embodiments. However, modifications and additions to theseembodiments will become apparent to those of ordinary skill in the artupon a reading of the foregoing description. It is intended that allsuch modifications and additions comprise a part of the presentinvention to the extent that they fall within the scope of the severalclaims appended hereto.

We claim:
 1. An expandible intervertebral fusion device comprising: afirst movable portion; a second movable portion; and a mechanism thatmoves the first movable portion and the second movable portion withrespect to each other to expand a dimension of the expandibleintervertebral fusion device, wherein the first movable portionincludes: a top wall, a bottom wall, and two sidewalls defining an openspace capable of receiving bone filling for the biological bone fusion;and an internal screw guide having an entry opening and an exit opening,the entry opening formed only in a top surface of the top wall and theexit opening formed at least partially in a bottom surface of the topwall and at least partially in a side surface of the top wall.
 2. Thedevice of claim 1, wherein the first movable portion slides with respectto the second movable portion.
 3. The device of claim 1, wherein thefirst movable portion pivots with respect to the second movable portion.4. The device of claim 1, wherein the first movable portion translateslinearly away from the second movable portion.
 5. The device of claim 1,wherein the first movable portion slides at an angle with respect to thesecond movable portion.
 6. The device of claim 1, wherein the mechanismincludes a threaded rod mechanism.
 7. The device of claim 1, wherein thesecond movable portion includes an open space capable of receiving bonefilling for the biological bone fusion.
 8. The device of claim 1,wherein one of the first movable portion and the second movable portionincludes an indentation to accommodate a component of a placement tool.9. The device of claim 1, wherein the first movable portion and thesecond movable portion can be adjusted by using a threaded rod as awedge to pivot components within the device.
 10. The device of claim 1,wherein the first movable portion and the second movable portion can beadjusted using a wedge device.
 11. The device of claim 1, wherein themechanism separates the first movable portion from the second movableportion.
 12. The device of claim 1, wherein the second movable portionincludes a second internal screw guide.
 13. The device of claim 1,wherein one of the first movable portion and the second movable portionincludes a tapered edge to allow contoured insertion into the discspace.
 14. The device of claim 1, wherein the first movable portion andthe second movable portion can be adjusted using a threaded rod coupledto a scissor-jack linkage.
 15. The device of claim 1, wherein the firstmovable portion and the second movable portion can be held together byfasteners.
 16. The device of claim 1, wherein the mechanism includes aworm drive or a worm gear.
 17. The device of claim 1, wherein themechanism includes a worm drive that turns a gear that acts as a wedgeto expand the device.
 18. The device of claim 1, further comprisingfasteners and retaining rings containing and constraining the devicepieces.
 19. The device of claim 1, wherein the mechanism includes a wormdrive to turn a gear that acts as a wedge to expand the device.
 20. Thedevice of claim 1, wherein the first movable portion and the secondmovable portion can be adjusted by a worm gear coupled to an internallythreaded spur gear which, upon rotation, linearly advances a threadedcomponent.
 21. The device of claim 1, wherein first and second screwmembers are medially aligned.
 22. The device of claim 1, wherein atleast one of first and second screw members is laterally aligned. 23.The device of claim 3, wherein both first and second screw members arelaterally aligned.
 24. The device of claim 1, wherein one of first andsecond screw members is laterally aligned and an other screw member ismedially aligned.
 25. The device of claim 1, wherein each of the firstmovable portion and the second movable portion has a substantiallytriangularly shape.
 26. The device of claim 6, wherein the first movableportion and the second movable portion include a sliding rail and ridgedsurfaces.
 27. The device of claim 7, wherein the first movable portionand the second movable portion include holes for bone grafts.
 28. Thedevice of claim 8, wherein an adjuster includes a screw.
 29. The deviceof claim 1, wherein one of the first movable portion and the secondmovable portion includes a sliding rail, and wherein the other of thefirst movable portion and the second movable portion includes a railinsert that engages the sliding rail.
 30. The device of claim 1, whereinone of the first movable portion and the second movable portion includesa plurality of sliding rails disposed on a side facing the other of thefirst movable portion and the second movable portion, and wherein theother of the first movable portion and the second movable portionincludes a plurality of rail inserts that engage the plurality ofsliding rails.
 31. The device of claim 1, wherein one of the firstmovable portion and the second movable portion the includes an externalsurface having a plurality of ridges.
 32. The device of claim 1, whereineach of the first movable portion and the second movable portionincludes an external surface having a plurality of ridges.
 33. Thedevice of claim 1, wherein one of the first movable portion and thesecond movable portion includes a hole for bone grafts.
 34. The deviceof claim 1, wherein each of the first movable portion and the secondmovable portion the includes a hole for bone grafts.
 35. The device ofclaim 1, wherein one of the first movable portion and the second movableportion includes a plurality of holes for bone grafts.
 36. The device ofclaim 1, wherein an adjuster includes a screw that engages each of thefirst movable portion and the second movable portion.
 37. The device ofclaim 12, wherein the second movable portion includes a second top wall,and wherein the second internal screw guide of the second movableportion has an entry opening and an exit opening, the entry openingformed only in a top surface of the second top wall.
 38. The device ofclaim 37, wherein the exit opening of the second internal screw guide ofthe second movable portion is formed at least partially in a bottomsurface of the second top wall and at least partially in a side surfaceof the second top wall.
 39. The device of claim 1, wherein the mechanismcomprises a threaded rotation screw extending between the first movableportion and the second movable portion that moves the first movableportion with respect to the second movable portion in response torotation of the threaded rotation screw, wherein first and secondindentations are defined on outer sides of the two sidewalls, whereinmeans for facilitating incorporation into and fusion with superior andinferior vertebral bodies is positioned on at least part of the twosidewalls of the first movable portion, and wherein the second movableportion has a second internal screw guide having an entry opening formedonly in a top surface of a top wall of the second movable portion andextending in a different direction than that of the internal screw guidesuch that the internal screw guide and second internal screw guidedirect screws into the superior and inferior vertebral bodies.
 40. Thedevice of claim 39, wherein the threaded rotation screw is positioned ina circular hole defined in the second movable portion.
 41. The device ofclaim 39, and further comprising means for promoting segmental spinalfusion.
 42. A system comprising the device of claim 39, wherein thesystem further comprises: a tool comprising: an elongate shaft; firstand second gripper prongs that are sized and positioned such that thefirst gripper prong engages the first indentation and the second gripperprong engages the second indentation when the tool engages the device;and a tool screw guide defining first and second screw trajectoryguides, wherein the first screw trajectory guide aligns with the firstinternal screw guide and guides a direction of insertion of a screw whenthe tool is engaged with the device, wherein the first and secondgripper prongs extend distally past the tool screw guide on oppositesides of the tool screw guide; and a screwdriver sized and configuredfor driving screws through the first and second internal screw guideswhile the tool is holding the device between first and second vertebralbodies.
 43. The system of claim 42, wherein the first and second screwtrajectory guides are defined in opposite sides of the tool screw guidewith each of the first and second screw trajectory guides having apartially tubular shape that is curved on one side and open on anopposite side.
 44. The device of claim 39, and further comprising meansfor sliding the first movable portion with respect to the second movableportion when the threaded rotation screw is turned.
 45. The device ofclaim 44, and further comprising means for retaining the threadedrotation screw.
 46. The device of claim 39, wherein the device isconfigured such that rotation of the threaded rotation screw can move atop wall of the second movable portion above the top wall of the firstmovable portion.
 47. An expandible intervertebral fusion devicecomprising: a first movable body; a second movable body; and means formoving the first movable body with respect to the second movable body toexpand a dimension of the expandible intervertebral fusion device,wherein the first movable body includes: a top wall, a bottom wall, andtwo sidewalls defining an open space capable of receiving bone fillingfor the biological bone fusion; and an internal screw guide having anentry opening and an exit opening, the entry opening formed only in atop surface of the top wall and the exit opening formed at leastpartially in a bottom surface of the top wall and at least partially ina side surface of the top wall.
 48. An expandible intervertebral fusiondevice comprising: a first movable portion; a second movable portion;and a mechanism that moves the first movable portion and the secondmovable portion with respect to each other to expand a dimension of theexpandible intervertebral fusion device, wherein the first movableportion includes a first top wall, a first bottom wall, a firstsidewall, and a second sidewall defining a first open space capable ofreceiving bone filling for the biological bone fusion, wherein thesecond movable portion includes a second top wall, a second bottom wall,a third sidewall, and a fourth sidewall defining a second open spacecapable of receiving bone filling for the biological bone fusion,wherein the first top wall of the first moveable portion and the secondtop wall of the second moveable portion cooperate to form a top wall ofthe expandible intervertebral fusion device, wherein the first movableportion includes a first internal screw guide having an entry openingand an exit opening, the entry opening formed entirely between all edgesof a top surface of the first top wall when viewed from a directionperpendicular to a plane of the top surface of the first top wall andthe exit opening formed at least partially in a bottom surface of thefirst top wall and at least partially in a side surface of the first topwall, and wherein the second movable portion includes a second internalscrew guide having an entry opening and an exit opening, the entryopening formed entirely between all edges of a top surface of the secondtop wall when viewed from a direction perpendicular to a plane of thetop surface of the second top wall and the exit opening formed at leastpartially in a bottom surface of the second top wall and at leastpartially in a side surface of the second top wall.
 49. The device ofclaim 48, wherein the mechanism comprises a threaded rotation screwextending between the first movable portion and the second movableportion that moves the first movable portion away from the secondmovable portion in response to rotation of the threaded rotation screw,wherein a circular hole extend into to the top wall of the expandibleintervertebral fusion device in a direction substantially normal to thetop wall of the expandible intervertebral fusion device and positionedbetween the first internal screw guide and the second internal screwguide, wherein a first indentation is defined on a first outer side ofthe first sidewall and a second indentation is defined on a second outerside of the second sidewall and is positioned opposite of the firstindentation, and wherein the first open space capable of receiving bonefilling extends continuously from an inner surface of the first sidewallto an inner surface of the second sidewall and extends continuously froman inner surface of the top wall to an inner surface of the bottom wall.50. the device of claim 49, wherein the threaded rotation screw ispositioned in the circular hole.
 51. The device of claim 48, wherein acircular hole extend into to the top wall of the expandibleintervertebral fusion device in a direction substantially normal to thetop wall of the expandible intervertebral fusion device and positionedbetween the first internal screw guide and the second internal screwguide, wherein a first indentation is defined on a first outer side ofthe first sidewall and a second indentation is defined on a second outerside of the second sidewall and is positioned opposite of the firstindentation, and wherein the first open space capable of receiving bonefilling extends continuously from an inner surface of the first sidewallto an inner surface of the second sidewall and extends continuously froman inner surface of the top wall to an inner surface of the bottom wall.52. The device of claim 51, and further comprising means for promotingsegmental spinal fusion.
 53. The device of claim 51, and furthercomprising means for facilitating incorporation into and fusion withsuperior and inferior vertebral bodies.
 54. The device of claim 53,wherein the means is positioned at least partially on the first sidewalladjacent the exit opening of the first internal screw guide and on thefourth sidewall adjacent the exit opening of the second internal screwguide.
 55. The device of claim 48, wherein a first indentation isdefined on a first outer side of the first sidewall and a secondindentation is defined on a second outer side of the second sidewall andis positioned opposite of the first indentation, wherein the first openspace capable of receiving bone filling extends continuously from aninner surface of the first sidewall to an inner surface of the secondsidewall and extends continuously from an inner surface of the top wallto an inner surface of the bottom wall, wherein each of the first andsecond movable portions comprise means for facilitating incorporationinto and fusion with superior and inferior vertebral bodies, and whereinthe means is positioned on each of the first top wall, the second topwall, the first bottom wall, the second bottom wall, and the first,second, third and fourth sidewalls, wherein a first portion of the meansis positioned on the side surface of the first top wall between the exitopening of the first internal screw guide and the top surface of thefirst top wall, and wherein a second portion of the means is positionedon the side surface of the second top wall between the exit opening ofthe second internal screw guide and the top surface of the second topwall.